The Many Meanings of تا

01

Until, Up To

With a time or a place, it marks the far end of a stretch.

• ⁧اَز ژانویِه تا مارس بایَد کُت بِپوشَم.⁩

  az žânviye tâ mârs bâyad kot bepušamaz zhânviye tâ mârs bâyad kot bepushamaz žanvyy ta mars bayd kt bpvšm

  From January until March I have to wear a coat.

• ⁧مُستَقیم راه بِرَوید تا یِک ساختِمانِ زَرد رَنگ را بِبینید.⁩

  mostaqim râh beravid tâ yek sâxtemân-e zard rang râ bebinidmostaqim râh beravid tâ yek sâkhtemân-e zard rang râ bebinidmstqym rah brvyd ta yk saxtman-a zrd rng ra bbynyd

  Walk straight on until you see a yellow building.

02

So That

With a subjunctive after it, ⁧⁧تا⁩⁩ (tâtâta) states a purpose - why the first thing is being done.

• ⁧اَلان دارَم دَرس می‌خوانَم تا بِتَوانَم اِمتِحان بِدَهَم.⁩

  alân dâram dars mi-xânam tâ betavânam emteḥân bedahamalân dâram dars mi-khânam tâ betavânam emtehân bedahamalan darm drs my-xanm ta btvanm amtḥan bdhm

  I am studying now so that I can sit the exam.

• ⁧او دَر را باز می‌کُنَد تا مَن بِتَوانَم داخِل بیایَم.⁩

  u dar râ bâz mi-konad tâ man betavânam dâxel biyâyamu dar râ bâz mi-konad tâ man betavânam dâkhel biyâyamav dr ra baz my-knd ta mn btvanm daxl byyaym

  She opens the door so that I can come in.

• ⁧تَماس گِرِفتَم تا بِه شُما اِطِّلاع دَهَم.⁩

  tamâs gereftam tâ be šomâ eṭṭelâʿ dahamtamâs gereftam tâ be shomâ ettelâ' dahamtmas grftm ta b šma aṭṭlaʿ dhm

  I called in order to let you know.

Both this and "until" can take a subjunctive, so the verb alone does not settle it. Ask whether the first action is done in order to bring the second about, as studying is done to pass the exam, or simply lasts up to it, as the walking lasts until the building comes into view.

03

As Long As, Until Such Time As

Combined with ⁧⁧وَقتی کِه⁩⁩ (vaqti kevaqti kevqty k) it sets a limit on how long something holds.

• ⁧تا وَقتی کِه گُواهینامِه‌یِ رانَندِگی نَگیرَم، نِمی‌تَوانَم رانَندِگی کُنَم.⁩

  tâ vaqti ke govâhinâme-ye rânandegi nagiram nemi-tavânam rânandegi konamtâ vaqti ke govâhinâme-ye rânandegi nagiram nemi-tavânam rânandegi konamta vqty k gvahynam-y ranndgy ngyrm nmy-tvanm ranndgy knm

  Until I get a driving licence, I cannot drive.

04

A Counter

Quite separately, ⁧⁧تا⁩⁩ (tâtâta) stands between a number and its noun as a general counter, rather as English says "three head of cattle".

• ⁧مَن بایَد سِه تا خُودکارِ جَدید بِخَرَم.⁩

  man bâyad se tâ xodkâr-e jadid bexaramman bâyad se tâ khodkâr-e jadid bekharammn bayd s ta xdkar-a jdyd bxrm

  I must buy three new pens.

• ⁧نَه، فَقَط چَندتا.⁩

  na faqaṭ čandtâna faqat chandtân fqṭ čndta

  No, just a few.

It adds no meaning at all here and can be left out. It is extremely common in speech.

05

Than

After a comparative, ⁧⁧تا⁩⁩ (tâtâta) can introduce what is being compared against, as an alternative to ⁧⁧اَز⁩⁩ (az).

• ⁧مَن بیشتَر فَرانسَوی صُحبَت می‌کُنَم تا اِسپانیایی.⁩

  man bištar farânsavi ṣoḥbat mi-konam tâ espâniyâyiman bishtar farânsavi sohbat mi-konam tâ espâniyâyimn byštr fransvy ṣḥbt my-knm ta aspanyyayy

  I speak more French than Spanish.